<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
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    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    //88.56%
    var isPalindrome = function(s) {
        let arr = [];
        for(let i of s){
            if((i.toLowerCase() >= 'a' && i.toLowerCase() <= 'z') || (i >= '0' && i <= '9')){
                arr.push(i.toLowerCase());
            }
        }
        let pre = arr.join('');
        let rev = arr.reverse().join('');
        return pre==rev?true:false;
    };  
    let s = "0P";
    console.log(isPalindrome(s));
    
</script>
</html>